Thermal treatment is used for treating a number of medical conditions, from sports injuries to infections to cancer. In a typical thermal treatment, thermal energy is applied to a subject's tissues in order to raise their temperature a few degrees above normal body temperature. Many types of pathogens and diseased cells are killed or are rendered vulnerable to medicines (e.g., chemotherapy) or the body's own immune system when exposed to higher temperatures. One form of thermal treatment involves applying heat to the body's exterior in the vicinity of the area to be treated, such as by applying heating blankets or heating units. However, such treatments heat all tissues in the vicinity of the applied heat, and thus may adversely affect surrounding healthy tissue. Another form of thermal treatment heats tissues within a body by exposing them to microwave radiation which raises the temperature of tissues by exciting water molecules within them, much as a microwave oven does to food. However, this thermal treatment method heats all tissues within the path of the microwave radiation, and thus also can adversely affect surrounding healthy tissues.
Another commonly used method for treating tissues within a body involves exposing the tissue to ionizing radiation, such as X-rays and gamma rays. As is well-known, tumors are frequently treated by exposing the tumor tissue to a series of narrow X-ray or gamma-ray beams, with each exposure made at several different exposure angles. This process exposes the tumor tissue at the convergence of the several beams to a high dose of radiation while exposing the rest of the body to a lower total dose (i.e., approximately the dose associated with a single beam exposure).
In addition, such methods require careful positioning and calibration of the emitter(s), with many high precision moving parts. While such treatment methods can be highly effective, such multibeam methods cannot be applied to thermal treatments employing microwave radiation since the objective in thermal treatments is to raise the tissue temperature for a period of time which requires continuous exposure to the microwave radiation.